1. Field of the Invention
This invention relates to adhesive compositions. More particularly, it relates to anaerobic curing compositions activatable, with respect to polymerization, by exposure to suitable radiation, which may be in the ultraviolet or visible region of the spectrum.
2. The Prior Art
A drawback with anaerobic curable adhesives is that they are extremely dependent on the substrate used and on the gap size between the two parts that are to be adhered together. When inactive substrates (e.g. glass or brass) or large gaps occur when using anaerobic adhesives, weak bonds or no bonds at all are obtained. This problem is normally overcome by using either a heat cure or a two-part adhesive or an activator pre-applied as a spray from a dilute solvent solution to one or both substrates. A heat cure is expensive; two part systems introduce problems of mixing, and pre-applied primers can lead to noxious fumes and vapors. The invention seeks, among its objects, to ameliorate or overcome some or all of the above recited disadvantages by providing a composition which may be used as a one-part adhesive or sealant.